If you fit a standard least squares model to World Gross using Rotten Tomatoes Score, Audience Score, and Genre as predictors, the residuals are highly heteroskedastic. (This is typical of financial data.) Use a log transformation to better satisfy the regression assumption of equal variance.

11.

Right-click on World Gross in the Select Columns list and select Transform > Log.

Recall that because of missing values, Genre is a nominal variable with eight levels. In the Current Estimates table, Genre is represented by seven terms. This is appropriate, because Genre has eight levels. The first two terms that represent Genre are described below. Subsequent terms are defined in a similar fashion.

The first term that appears is Genre{Drama&Thriller&Horror&Fantasy&Romance&Comedy-Action&Animation}. This variable has the form Genre{A1 - A2}, where A1 and A2 are separated by a minus sign. The notation indicates that the maximum separation in terms of sum of squares between groups occurs between the following two sets of levels:

If you include the term Genre{Drama&Thriller&Horror&Fantasy&Romance&Comedy-Action&Animation} in a model, a column representing that term is added to the data table. In the example, you saved this column to the data table. The column shows the following values:

The second term that appears is Genre{Drama-Thriller&Horror&Fantasy&Romance&Comedy}. This set of levels is entirely contained in the first split for the first term (A1). The notation contrasts the levels:

When you use the Combine rule or the Restrict rule, a term cannot enter the model unless all the terms above it in the hierarchy have been entered. For example, if you enter Genre{Action-Animation}, then JMP will enter Genre{Drama&Thriller&Horror&Fantasy&Romance&Comedy-Action&Animation} as well.

When you use the Whole Effects rule and enter any one of the Genre terms, all of the Genre terms are entered.